package com.dubious.interview.euler;

import java.util.ArrayList;
import java.util.List;

public class Problem11 {

    //@formatter:off
    /**
     * In the 20x20 grid below, four numbers along a diagonal line have been marked in red.
     *
     *   08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
     *   49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
     *   81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
     *   52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
     *   22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
     *   24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
     *   32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
     *   67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
     *   24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
     *   21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
     *   78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
     *   16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
     *   86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
     *   19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
     *   04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
     *   88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
     *   04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
     *   20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
     *   20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
     *   01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
     *   
     *  The product of these numbers is 26  63  78  14 = 1788696.
     *   
     *  What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 2020 grid?
     * @param args
     */
    //@formatter:on
    public static void main(String[] args) {

        String[] lines =
                new String[] {"08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08",
                        "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00",
                        "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65",
                        "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91",
                        "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80",
                        "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50",
                        "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70",
                        "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21",
                        "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72",
                        "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95",
                        "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92",
                        "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57",
                        "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58",
                        "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40",
                        "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66",
                        "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69",
                        "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36",
                        "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16",
                        "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54",
                        "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48" };

        // convert string to lists
        List<List<Integer>> matrix = new ArrayList<List<Integer>>(lines.length);
        for (String line : lines) {
            String[] entries = line.split(" ", 0);
            List<Integer> row = new ArrayList<Integer>(entries.length);

            for (int i = 0; i < entries.length; i++) {
                row.add(Integer.parseInt(entries[i]));
            }

            matrix.add(row);
        }

        System.out.println("Max Adjacent Product: " + getMaxAdjacentProduct(matrix, 4));
    }

    public static int getMaxAdjacentProduct(List<List<Integer>> matrix, int numEntries) {
        int maxAdjacentSum = 0;

        int numColumns = matrix.size();
        int numRows = matrix.get(0).size();
        for (int i = 0; i < numRows; i++) {
            for (int j = 0; j < numColumns; j++) {
                boolean canRight = (j <= numColumns - numEntries);
                boolean canLeft = (j >= numEntries);
                boolean canDown = (i <= numRows - numEntries);
                //@formatter:off
                // right
                if(canRight)
                {
                    maxAdjacentSum 
                        = getProductMax(maxAdjacentSum, matrix, i, j, i, j+1, i, j+2, i, j+3);
                }
                // down
                if(canDown)
                {
                    maxAdjacentSum 
                        = getProductMax(maxAdjacentSum, matrix, i, j, i+1, j, i+2, j, i+3, j);
                    
                }
                // down-right
                if(canDown && canRight)
                {
                    maxAdjacentSum 
                        = getProductMax(maxAdjacentSum, matrix, i, j, i+1, j+1, i+2, j+2, i+3, j+3);
                }   
                // down-left
                if(canDown && canLeft)
                {
                    maxAdjacentSum 
                        = getProductMax(maxAdjacentSum, matrix, i, j, i+1, j-1, i+2, j-2, i+3, j-3);
                }
                //@formatter:on
            }
        }

        return maxAdjacentSum;
    }

    public static int getProductMax(
            int currentProductMax,
            List<List<Integer>> matrix,
            int aR,
            int aC,
            int bR,
            int bC,
            int cR,
            int cC,
            int dR,
            int dC) {
        int product =
                matrix.get(aR).get(aC) * matrix.get(bR).get(bC) * matrix.get(cR).get(cC)
                        * matrix.get(dR).get(dC);
        if (product > currentProductMax) {
            System.out.println("New Max (" + matrix.get(aR).get(aC) + ","
                    + matrix.get(bR).get(bC) + "," + matrix.get(cR).get(cC) + ","
                    + matrix.get(dR).get(dC) + ") with product " + product);
            return product;
        } else {
            return currentProductMax;
        }
    }
}
